Make most of functions const correct (#714)

* Make most of the functions const correct

Used clang-tidy and sonarlint to help find places where const could
pretty easily applied. Also lot of hand work.

This commit does not yet touch handlers and typedefs of those.

* Fix Arduino uno handler_who_is() has extra parenthesis

For some reason there is extra parenthesis. Remove it this is more
likely buildable.

* Bugfix/bacapp: Fix uninitilized array_index

We have changed bacapp_snprintf_value() to be const correct. After that
we got

```
/home/runner/work/bacnet-stack/bacnet-stack/src/bacnet/bacapp.c:3183:27: warning: 4th function call argument is an uninitialized value [core.CallAndMessage]
                ret_val = bacapp_snprintf_weeklyschedule(
                          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1 warning generated.
```

So analyzer could now spot that we do not actually initilize array_index
at all. Fix this by setting array_index to zero. Note that I actually do
not know if zeroing is right thing to do here. I choose zero as if this
has worked before it is most likely that it will work with zero value.

* cmake: Add and ignore Wwrite-strings compiler option

Wwrite-strings helps find places where const correctness is broken.

Example it will warn about these

```C

void func1(char* str);

func("test") /* "test" is const so we should not pass it to func1().

char* func2()
{
  return "test"; /* func2() should return const char*.
}
```

We still need to ignore it as not all are fixed but let's add it already
so we remember that it should be opened at some point.

---------

Co-authored-by: Kari Argillander <kari.argillander@fidelix.com>

ports/bsd/bip-init.c

@@ -162,7 +162,7 @@ void bip_get_broadcast_address(BACNET_ADDRESS *dest)
  *
  * @param addr - network IPv4 address
  */
-bool bip_set_addr(BACNET_IP_ADDRESS *addr)
+bool bip_set_addr(const BACNET_IP_ADDRESS *addr)
 {
     (void)addr;
     /* not something we do within this driver */
@@ -189,7 +189,7 @@ bool bip_get_addr(BACNET_IP_ADDRESS *addr)
  * @param addr - network IPv4 address
  * @return true if the address was set
  */
-bool bip_set_broadcast_addr(BACNET_IP_ADDRESS *addr)
+bool bip_set_broadcast_addr(const BACNET_IP_ADDRESS *addr)
 {
     (void)addr;
     /* not something we do within this driver */
@@ -257,7 +257,8 @@ uint8_t bip_get_subnet_prefix(void)
  * @return Upon successful completion, returns the number of bytes sent.
  *  Otherwise, -1 shall be returned and errno set to indicate the error.
  */
-int bip_send_mpdu(BACNET_IP_ADDRESS *dest, uint8_t *mtu, uint16_t mtu_len)
+int bip_send_mpdu(
+    const BACNET_IP_ADDRESS *dest, const uint8_t *mtu, uint16_t mtu_len)
 {
     struct sockaddr_in bip_dest = { 0 };
 
@@ -276,7 +277,7 @@ int bip_send_mpdu(BACNET_IP_ADDRESS *dest, uint8_t *mtu, uint16_t mtu_len)
     /* Send the packet */
     debug_print_ipv4(
         "Sending MPDU->", &bip_dest.sin_addr, bip_dest.sin_port, mtu_len);
-    return sendto(BIP_Socket, (char *)mtu, mtu_len, 0,
+    return sendto(BIP_Socket, (const char *)mtu, mtu_len, 0,
         (struct sockaddr *)&bip_dest, sizeof(struct sockaddr));
 }
 
@@ -472,7 +473,8 @@ static char *ifname_default(void)
  * @param addr [out] The netmask addr, broadcast addr, ip addr.
  * @param request [in] addr broadaddr netmask
  */
-static int get_local_address(char *ifname, struct in_addr *addr, char *request)
+static int get_local_address(
+    const char *ifname, struct in_addr *addr, const char *request)
 {
     char rv = '\0'; /* return value */
 
@@ -543,7 +545,7 @@ int bip_set_broadcast_binding(
  * @param ifname [in] The named interface to use for the network layer.
  *        Eg, for MAC OS X, ifname is en0, en1, and others.
  */
-void bip_set_interface(char *ifname)
+void bip_set_interface(const char *ifname)
 {
     struct in_addr local_address;
     struct in_addr broadcast_address;
@@ -602,7 +604,7 @@ void bip_set_interface(char *ifname)
     }
 }
 
-static int createSocket(struct sockaddr_in *sin)
+static int createSocket(const struct sockaddr_in *sin)
 {
     int status = 0; /* return from socket lib calls */
     int sockopt = 0;

ports/bsd/bip6.c

@@ -181,7 +181,7 @@ void bip6_get_my_address(BACNET_ADDRESS *addr)
  *
  * @param addr - network IPv6 address
  */
-bool bip6_set_addr(BACNET_IP6_ADDRESS *addr)
+bool bip6_set_addr(const BACNET_IP6_ADDRESS *addr)
 {
     return bvlc6_address_copy(&BIP6_Addr, addr);
 }
@@ -201,7 +201,7 @@ bool bip6_get_addr(BACNET_IP6_ADDRESS *addr)
  *
  * @param addr - network IPv6 address
  */
-bool bip6_set_broadcast_addr(BACNET_IP6_ADDRESS *addr)
+bool bip6_set_broadcast_addr(const BACNET_IP6_ADDRESS *addr)
 {
     return bvlc6_address_copy(&BIP6_Broadcast_Addr, addr);
 }
@@ -227,7 +227,8 @@ bool bip6_get_broadcast_addr(BACNET_IP6_ADDRESS *addr)
  * @return Upon successful completion, returns the number of bytes sent.
  *  Otherwise, -1 shall be returned and errno set to indicate the error.
  */
-int bip6_send_mpdu(BACNET_IP6_ADDRESS *dest, uint8_t *mtu, uint16_t mtu_len)
+int bip6_send_mpdu(
+    const BACNET_IP6_ADDRESS *dest, const uint8_t *mtu, uint16_t mtu_len)
 {
     struct sockaddr_in6 bvlc_dest = { 0 };
     uint16_t addr16[8];
@@ -252,7 +253,7 @@ int bip6_send_mpdu(BACNET_IP6_ADDRESS *dest, uint8_t *mtu, uint16_t mtu_len)
     bvlc_dest.sin6_scope_id = BIP6_Socket_Scope_Id;
     debug_print_ipv6("Sending MPDU->", &bvlc_dest.sin6_addr);
     /* Send the packet */
-    return sendto(BIP6_Socket, (char *)mtu, mtu_len, 0,
+    return sendto(BIP6_Socket, (const char *)mtu, mtu_len, 0,
         (struct sockaddr *)&bvlc_dest, sizeof(bvlc_dest));
 }
 

ports/bsd/datetime-init.c

@@ -27,8 +27,7 @@
  * @param utc - True for UTC sync, False for Local time
  * @return True if time is set
  */
-void datetime_timesync(
-    BACNET_DATE *bdate, BACNET_TIME *btime, bool utc)
+void datetime_timesync(BACNET_DATE *bdate, BACNET_TIME *btime, bool utc)
 {
     (void)bdate;
     (void)btime;

ports/bsd/rs485.c

@@ -396,7 +396,7 @@ bool RS485_Set_Baud_Rate(uint32_t baud)
  *****************************************************************************/
 void RS485_Send_Frame(
     struct mstp_port_struct_t *mstp_port, /* port specific data */
-    uint8_t *buffer, /* frame to send (up to 501 bytes of data) */
+    const uint8_t *buffer, /* frame to send (up to 501 bytes of data) */
     uint16_t nbytes)
 { /* number of bytes of data (up to 501) */
     uint32_t turnaround_time = Tturnaround * 1000;

ports/bsd/rs485.h

@@ -30,8 +30,8 @@ void RS485_Initialize(void);
 BACNET_STACK_EXPORT
 void RS485_Send_Frame(
     struct mstp_port_struct_t *mstp_port, /* port specific data */
-    uint8_t *buffer, /* frame to send (up to 501 bytes of data) */
-    uint16_t nbytes); /* number of bytes of data (up to 501) */
+    const uint8_t *buffer,  /* frame to send (up to 501 bytes of data) */
+    uint16_t nbytes);       /* number of bytes of data (up to 501) */
 
 BACNET_STACK_EXPORT
 void RS485_Check_UART_Data(